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Simulation is diverging troubleshooting; (boundary conditions) |
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Christoph Trier
Join Date: Mar 2024
Posts: 12
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Hey guys,
First, I uploaded my case to my GitHub: https://github.com/Lorddrinkalot/openfoam_forum I am trying to simulate the flow through a fusion blacket using a very simple geometry, L_shape. I am using the bouyantPimpleMhdFoam solver. The bouyantPimpleFoam can also be used for cases without MHD, and the same problem is present. EquationofState is Boussinesq. I have split my Simulation into simple steps for better troubleshooting. Starting with the normal flow with no Heat source and no magnetic field, this case is converging and working fine. For the second part, I've added the FvOption file for my Heat source. However, the Simulation is diverging and I'm still trying to pinpoint the issue. I thought it would be beneficial to share it here to receive some valuable feedback from you all. Your insights are highly appreciated. I think that my boundary conditions (p_rgh and U) are not "good enough" anymore for the second part with the heat source switched on. (have some images in the attachments) Another option would be the mesh; however, checkMesh says the mesh is ok, and I also agree with this. Also, when I refine the mesh, the problem stays. Best regards Christoph Code:
/*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 2312 | | \\ / A nd | Website: www.openfoam.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : _c39a0f64-20231220 OPENFOAM=2312 version=2312 Arch : "LSB;label=32;scalar=64" Exec : checkMesh Date : Jun 17 2024 Time : 12:35:35 Host : DESKTOP-FNK6QBM PID : 11968 I/O : uncollated Case : /home/christoph/OpenFOAM/christoph-v2312/run/L_shape nProcs : 1 trapFpe: Floating point exception trapping enabled (FOAM_SIGFPE). fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 5, maxFileModificationPolls 20) allowSystemOperations : Allowing user-supplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 0 Check mesh... Time = 0 Mesh stats points: 150381 faces: 426100 internal faces: 401900 cells: 138000 faces per cell: 6 boundary patches: 5 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 138000 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 0 Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology inlet 600 651 ok (non-closed singly connected) outlet 600 651 ok (non-closed singly connected) Wall_out 8100 8401 ok (non-closed singly connected) Wall_side 9200 9702 ok (non-closed singly connected) Wall_inside 5700 5921 ok (non-closed singly connected) ".*" 24200 24202 ok (closed singly connected) Checking faceZone topology for multiply connected surfaces... No faceZones found. Checking basic cellZone addressing... No cellZones found. Checking basic pointZone addressing... No pointZones found. Checking geometry... Overall domain bounding box (0 0 0) (1.133 2.135 0.1616) Mesh has 3 geometric (non-empty/wedge) directions (1 1 1) Mesh has 3 solution (non-empty) directions (1 1 1) Boundary openness (-2.61002e-16 -2.41706e-18 5.65942e-15) OK. Max cell openness = 1.53505e-16 OK. Max aspect ratio = 6.88459 OK. Minimum face area = 4.19083e-05. Maximum face area = 0.000527534. Face area magnitudes OK. Min volume = 5.96145e-07. Max volume = 2.84165e-06. Total volume = 0.229287. Cell volumes OK. Mesh non-orthogonality Max: 0 average: 0 Non-orthogonality check OK. Face pyramids OK. Max skewness = 1.66477e-13 OK. Coupled point location match (average 0) OK. Mesh OK. End Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: v2212 | | \\ / A nd | Website: www.openfoam.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [1 -1 -2 0 0 0 0]; internalField uniform 0; boundaryField { inlet { type zeroGradient; //type fixedFluxPressure; //value uniform 0; } outlet { //type totalPressure; //p0 uniform 0; //U U; //rho rho_0; type fixedValue; value uniform 0; //type fixedFluxPressure; //value uniform 0; //type inletOutlet; //outletInlet //inletValue uniform 0; } Wall_side { type zeroGradient; } Wall_out { type zeroGradient; } Wall_inside { type zeroGradient; } } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: v2212 | | \\ / A nd | Website: www.openfoam.com | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { inlet { type fixedValue; value uniform (0.02 0 0); } outlet { type zeroGradient; //type pressureInletOutletVelocity; //value uniform (0 0 0); } Wall_side { type noSlip; } Wall_out { type noSlip; } Wall_inside { type noSlip; } } // ************************************************************************* // |
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boundary, diverging |
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